It is indicated that the sealing capacity depends on the contact characteristics-the relative contact area and the gap density in the joint. To determine the contact characteristics, a discrete roughness model is used in the form of a set of spherical segments, the distribution of which in height is related to the bearing curve described by the regularized beta function. The contact of a single asperity is considered with taking into account the influence of the remaining contacting asperities. The equations for determining the relative contact area and gap density in the joint depending on the dimensionless force parameters for elastic and elastic-plastic contacts are provided.

Abstract.A penetration of spherical asperity into the elastic-plastic hardening half-space is described. The elastic-plastic material properties correspond to Hollomon's power law. In this case the empirical Meyer law relating a spherical indentation load with an indentation diameter d is used. Initially, the Meyer law is not related to the mechanical characteristics of the test material. The study used the relations between the strain hardening exponent n and the Meyer law constant obtained by S.I. Bulychev. The effects relating to elastic punching and plastic displacement of material are taked into account. It is shown that there is no need to define Meyer law constants. Expressions relating the value of the relative load magnitude to the relative indenter penetration magnitude are presented. The scope of application of the proposed equations is defined. A comparison of the obtained results with the experimental data and published data of the finite element analysis is given.

Initially, the contact of a single spherical asperity is considered with taking into account the influence of the remaining contacting asperities. It is assumed that the influence of the remaining contacting asperities is equal to the action of the uniform loading qc outside the asperity contour. This made possible to solve the contact problem as an axisymmetric one. An equation for the pressure distribution at the contact area is obtained. To determine the contact characteristics, a discrete roughness model is used, the surface bearing curve of which is described by a regularized beta function. The relative contact area and the gap density in the joint are determined depending on the dimensionless force elastic-geometric parameter fq. When determining the gap density in the joint, the displacements of the rough surface and half-space are taken into account. It is shown that the contact characteristics do not depend on the values of the regularized beta function parameters p and q.

No abstract

It is assumed that the influence of the remaining contacting asperities is equal to the action of the uniform loading q c outside the asperity contour. Three parameters are suggested as possible criteria of occurrence of plastic deformation in the subsurface layer of contact of a single asperity: critical value ε c in which the equivalent stress is equal to the yield point σ y ; the relative contact area η ip at which plastic deformations occur; the ratio of the maximum pressure at the contact area to the yield point σ y . For single asperities, the stability of the relative contact area at which plastic deformation begins is indicated. The criteria for plasticity characterizing respectively the onset of plastic deformation in the near-surface layer η p * and on the contact surface η ̅ p * areproposed. The values of the criteria do not depend on the loading conditions and are determined by the complex parameter f y characterizing the microgeometry of the asperities and the mechanical properties of the material.